Trunion discussion again......................

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SWilliams
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Trunion discussion again......................

Post by SWilliams »

OK so the trunion springs and both the plate and trunion shaft on the 2284 are worn enough to throw a cat through. I know the usual drill is weld up, grind back and tighten it up. BUT other than provide a flexible connection between the speed lever and the hydro, what purpose do the springs serve? Just as a test I used 4 heavy zip ties to "bypass" the springs and full control returned and it acted like my other hydrogear tractors with instant control.

If I replace the outer spring with a stiffer spring what happens other than faster wear?
Do they somehow compensate for heavier loads or correct for uphill/downhill speed issues?

I went back through a bunch of posts giving the size of the hole and how shimming was done, but nothing really gave a reason for the springs.
Owner of 129, 1641, 1863, 1864, 2263 (1863 W 22hp engine!) 2084 (2) and a 2284.

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Mcamp
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Re: Trunion discussion again......................

Post by Mcamp »

The springs are there to cushion the forward to reverse action.If you made it a solid connection you would have a very jerky hydro,i worked on one that was solid and it would pop wheelies and snap your neck if you were not gentle on the control.

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SWilliams
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Re: Trunion discussion again......................

Post by SWilliams »

That's the thing, the newer tractors use a solid connection and they are not jerky. Maybe the internal valving is different ? That's about what I figured, I'll have to play with different springs to get it the way I want it to work.
Owner of 129, 1641, 1863, 1864, 2263 (1863 W 22hp engine!) 2084 (2) and a 2284.

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BigMike
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Re: Trunion discussion again......................

Post by BigMike »

Dags hydros are only jerky when he is on them :lol:
I figured we haven't sparred for a while Dag :D

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dag1450
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Re: Trunion discussion again......................

Post by dag1450 »

:x what the heck does that mean........you saying..you want a piece of me? :x
127, 1650, 1572, 1872, 2072 . A mower, blower and blade for each.

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SWilliams
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Re: Trunion discussion again......................

Post by SWilliams »

OK so the springs are supposed to absorb the motion of the linkage and act like a shock absorber? Wonder what a urethane replacement would do.
Last edited by SWilliams on Fri Nov 24, 2017 9:23 pm, edited 1 time in total.
Owner of 129, 1641, 1863, 1864, 2263 (1863 W 22hp engine!) 2084 (2) and a 2284.

"In God we trust, All others pay CASH..."

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chzuck
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Re: Trunion discussion again......................

Post by chzuck »

I shimmed the spring with a flat washer, one on each end. It makes it a little jerky, but it does not slow up near as much on hills. I tried 2 washers on each end, but that was way to jerky for me.
Last edited by chzuck on Fri Nov 24, 2017 6:57 pm, edited 1 time in total.
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BigMike
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Re: Trunion discussion again......................

Post by BigMike »

Dag you just wait until festivus and the airing of grievances ;)

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Tom Scott
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Re: Trunion discussion again......................

Post by Tom Scott »

SWilliams wrote:If I replace the outer spring with a stiffer spring what happens other than faster wear?

A stiffer spring will make it more responsive, likely too responsive. The factory spring should be fine for most applications, but my loader 2182 is so heavy it needs more spring... we'll get back to this. A heavier spring will move less distance in the trunion slot; the wear rate should not be different, only the wear area will be more concentrated at the ends of the slots due to more limited movement.
SWilliams wrote:Do they somehow compensate for heavier loads or correct for uphill/downhill speed issues?
They don't compensate for heavier loads, but they see more force with heavier loads; the Sauer-Danfoss engineering info gives the specs for how much torque is fed back into the control arm based on hydro loading. So, in an application with real steep hills and heavy loads, such as my loader tractor, a heavier spring is justified. Over on the OCC site they identified a commonly available exhaust stud kit that includes a spring of similar dimensions that is stiffer. The part numbers are Dorman-Help! 03107 or NAPA 600-2411. Again, I wouldn't go to this unless you see the need I do. Even with a new factory spring, I sometimes can't back up with a loaded bucket... the rig is so heavy that the hydro reaction on the control arm compresses the factory spring without being moved far enough to reverse.

The lighter the spring, the smoother the action at the expense of speed on hills or heavy loads (to the point of no speed in reverse for my case...). The inner spring is longer and weaker, and is meant to ease you into the heavier spring. That is why the heavier outer spring does not touch at first, until you compress the inner spring some.
Mcamp wrote:The springs are there to cushion the forward to reverse action.If you made it a solid connection you would have a very jerky hydro,i worked on one that was solid and it would pop wheelies and snap your neck if you were not gentle on the control.
This... Mark is dead on, can't say it any better!
SWilliams wrote:That's the thing, the newer tractors use a solid connection and they are not jerky. Maybe the internal valving is different ?
Yes, if linkage is solid it must have hydraulic cushioning, which is really a good way of doing it.
BigMike wrote:Dags hydros are only jerky when he is on them
This... BM is dead on here, can't say this any better either! :lol:
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1872, 46", 50C decks, Haban dozer blade, 450 snow blower
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SWilliams
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Re: Trunion discussion again......................

Post by SWilliams »

Thanks Tom, I hadn't even thought to look at the book on that hydro. :beer:

I may weld it up and install the stiffer spring (I have some on the shelf !) Then just get used to it as I won't have a frame of reference for the OEM spring anyway.
Started adjusting the brakes, as it was they almost worked... Almost....
Owner of 129, 1641, 1863, 1864, 2263 (1863 W 22hp engine!) 2084 (2) and a 2284.

"In God we trust, All others pay CASH..."

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dag1450
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Re: Trunion discussion again......................

Post by dag1450 »

BigMike wrote:Dag you just wait until festivus and the airing of grievances ;)
:x were putting the pole up this weekend......so let the feats of strength begin! You and your Lloyd Braun (Tom) friend are going down..... :x
127, 1650, 1572, 1872, 2072 . A mower, blower and blade for each.

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cholloway
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Re: Trunion discussion again......................

Post by cholloway »

^^^^ Does this mean you're the "George" of this repartee? ^^^^
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dag1450
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Re: Trunion discussion again......................

Post by dag1450 »

:lol: Colin..no way! I'm Frank! MIke is George.....or Kruger :lol:
127, 1650, 1572, 1872, 2072 . A mower, blower and blade for each.

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BigMike
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Re: Trunion discussion again......................

Post by BigMike »

Just because my legal first name is George does NOT mean I am George.
I am a bumbling idiot some maybe I am Kruger! :lol:

DaveKamp
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Re: Trunion discussion again......................

Post by DaveKamp »

How'd your trunion situation turn out, Dag? My next steps on Loader-Mutt will be brake linkage and replacing the trunion with a solid link.

I believe the trunion spring compliance was probably more to reduce the amount of reaction shock placed on the S-R lever... without it, the SR lever would likely not stay in place. In my case, there is no S-R... it's a treadle, so there's no issue with available force. Like Tom notes, though, when the loader is loaded, the springs compress substantially.

One side note, is that the trunion spring arrangement does add a benefit for the unknowledgable- when there's a heavy load on the hydrostat, that causes reaction on the swashplate (which controls pump piston stroke). When a person pushes the swashplate forward, the swashplate's reaction load pushes back in proportion to pump PRESSURE, because you're demanding more VOLUME. This equates to power, but it also equates to drive RATIO.

When there's a heavy drawbar load, and it starts to pull the engine down substantially, the trunion's response (being more swashplate reaction) is to compress one spring, allowing the swashplate to go to a lower RATIO, which means it doesn't pull the engine down as hard, but rather, increases wheel torque at the cost of reaching for speed the motor can't handle.

In my case, when I'm operating, if it's pulling the engine down hard (and I'm not spinning wheels), I back off on the treadle, and it pulls through...

...or it twists off an axle... :oops:
Yes, I'm a Mad Scientist... but I'm usually happy, even when things ain't goin right.

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